1. Field of the Invention
The present invention relates to a pain measurement system and a method of measuring pain.
2. Description of the Related Art
Pain can be described generally in two ways. According to one approach, pain is expressed in terms of quality or type. For example, pain may be described as “burning pain”, “smarting pain”, “pricking pain”, etc. The other way of describing pain is based on the magnitude of pain. For example, pain may be described as “slight pain”, “unbearable pain”, etc.
The former pain expressions can easily be made if one is aware of a certain range of modifying words for pain. However, it is difficult to properly express magnitudes of pain because the sensation of pain is subjective and personal, and the degree to which one can tolerate pain is easily affected by cultural and psychological factors.
Nevertheless, an objective evaluation of pain is indispensable for diagnosing pain and judging therapeutic effects.
Heretofore, a visual analog scale based on an evaluation made by a patient has been used to determine the magnitude of a pain felt by the patient. For example, a straight line that is 10 cm long is drawn on a sheet of paper with one end of the line representing no pain and the other end intolerable pain. The patient puts a mark indicative of the magnitude of a pain actually felt by the patient on the straight line at a commensurate position along the scale of the straight line.
Although the above evaluating method is simple, it is subjective and has evaluation standards varying from patient to patient. This makes it difficult to compare measured magnitudes of pain between different patients.
Attempts have been made to measure a pain in terms of physiological reactions such as aspiration, heartbeat, blood pressure, etc. for objectively expressing the pain. However, those efforts have proven unsuccessful.